This application which is submitted on behalf of the International Committee of the 5th International Conference of Osteogenesis Imperfecta and sponsored by the Nuffield Departments of Medicine (NDM) and Orthopaedic Surgery (NDOS), University of Oxford, requests partial support for this conference. The conferences first held in Oxford, England in 1983 and 1985 and Pavia, Italy in 1988 and 1990, have provided an exciting forum for the rapidly increasing information on osteogenesis imperfecta (OU). Within the last two decades research into this crippling disease has fulfilled its potential, as a disorder due to mutations in the collagen genes, to provide detailed insights into the effects of collagen mutations on the skeleton (and other collagen- containing tissues), and to illuminate collagen biology. It has also given unexpected and exciting insights into the existence and effects of somatic and germ line mosaicism, and has suggested the possibility that such collagen gene mutations could contribute to more frequent polygenic disorders, such as osteoporosis and arthritis. The 5th OI meeting will come at a particularly opportune time in international research. Not only will it be an opportunity to review the numerous mutations which are now known to cause OI, but it will particularly be an occasion to discuss possible novel forms of treatment, such as gene therapy. Whilst much effort has gone into identifying collagen gene mutations in OI (and some skeletal dysplasias) it is now time to look again at the possibilities for the prevention and management of OI based on the knowledge which has now been established. The success of this residential conference will depend on open discussion of current information and future possibilities for the application of biochemical and molecular advances to the management of osteogenesis imperfecta. Ample opportunity will be provided for the discussion of up-to-date work by young investigators.